Optimal Captcha

[naypalm]

For some of my sites, I use a combination of 2 tests. One is an addition or subtraction problem. The other is the current btc price listed on the page. So far it has eluded bots but from time to time there is the occasional jackass.

[geforcelover]

Well i have a question too why the sites uses captcha .. and the company whihc provide cpathca coast for thier capthca?

[onlinepro]

Well i have a question too why the sites uses captcha .. and the company whihc provide cpathca coast for thier capthca?

Sites use chaptchas because it makes spamming and bots action harder.

[mix1234]

Hello,
what captcha solution are you using on your sites? I personally hate reCaptcha

Yes, reCaptcha is very annoying for the end-user. You can try to use "key captcha":



simple and fast, no text to type, not annoying. But I don't know if it's enough secure or not.

[zimmah]

I think http://www.minteye.com/ is best.
I like it because I don't need to use keyboard for it at all!

So this is combination of advertisement and captcha solving? (good idea if so)

Also it unfortunately seems english only.

Yes, it is ad.
What you mean english only? It is picture so I don't think users have to know english, since you don't have to read anything.
Everything users have to do is use that slider to make image look good, and click enter.

There is example of this chaptcha:

These are probably the least annoying of them all.
I also don't mind solve media usually as they are pretty readable usually.

[ondratra]

PoW may be able to solve the captcha problem.

Mining is CPU intensive. If a captcha was a script that mined to get a proof with difficultly X, then the cost of creating an account would outweigh the financial benefit of having said account.

But how would real person declare he is actually real??? Imho text captcha is kind of PoW anyway - or maybe better to call it "Proof of understanding"

You can hire a team through mechanical turk to solve proof-of-human captcha. The captcha is solved, but the account is still under automated control or exploited.

If you can attach an expense to an action, an expense which is unnoticed to a single individual taking a single action, but economically inviable to an entity seeking to exploit the action on mass for minor financial gain, then you have solved the problem. (Spam problem)

In first paragraph you said why exactly your second  paragraph is not possible. If it will be easy for single person he can always do it as job to support bot operation. 

[coinsolidation]

PoW may be able to solve the captcha problem.

Mining is CPU intensive. If a captcha was a script that mined to get a proof with difficultly X, then the cost of creating an account would outweigh the financial benefit of having said account.

But how would real person declare he is actually real??? Imho text captcha is kind of PoW anyway - or maybe better to call it "Proof of understanding"

You can hire a team through mechanical turk to solve proof-of-human captcha. The captcha is solved, but the account is still under automated control or exploited.

If you can attach an expense to an action, an expense which is unnoticed to a single individual taking a single action, but economically inviable to an entity seeking to exploit the action on mass for minor financial gain, then you have solved the problem. (Spam problem)

In first paragraph you said why exactly your second  paragraph is not possible. If it will be easy for single person he can always do it as job to support bot operation.  

The key is the number of repetitions, a single person taking a single action has no noticeable cost involved. Taking multiple actions the cost of production up, if the cost of production (time+electricity) becomes higher than the benefit of having say multiple accounts or spamming, then it doesn't become good business to do so.

It's that same as charging people to submit a form or send an email, there's a monetary value which makes spamming no longer viable.

note: just a random idea, to apply PoW to different problem spaces, could also be used for a voting system, where each vote has to be computationally harder than the last.

[ondratra]

Hello,
what captcha solution are you using on your sites? I personally hate reCaptcha

Yes, reCaptcha is very annoying for the end-user. You can try to use "key captcha":



simple and fast, no text to type, not annoying. But I don't know if it's enough secure or not.

It seems very breakable.

[ShibaWow]

no man..

use SolveMedia

it's simple and it even earns you some money

[sana8410]

what about a captcha that changes a question every week so that will it make it harder for bot programmers to keep up with the new questions and answers all the time.

[ShibaWow]

what about a captcha that changes a question every week so that will it make it harder for bot programmers to keep up with the new questions and answers all the time.

SolveMedia has a different captcha everytime..

[virtualx]

Hello,
what captcha solution are you using on your sites? I personally hate reCaptcha

Yes, reCaptcha is very annoying for the end-user. You can try to use "key captcha":



simple and fast, no text to type, not annoying. But I don't know if it's enough secure or not.

It seems very breakable.

An automated version of this would be possible, but then again - which spammer would develop a software application for that?

[ondratra]

Hello,
what captcha solution are you using on your sites? I personally hate reCaptcha

Yes, reCaptcha is very annoying for the end-user. You can try to use "key captcha":



simple and fast, no text to type, not annoying. But I don't know if it's enough secure or not.

It seems very breakable.

An automated version of this would be possible, but then again - which spammer would develop a software application for that?

Anyone that evaluate access to system as valuable.

[Alex_green]

Optimal Captcha- it's number

[ondratra]

Optimal Captcha- it's number

wtf are you saying?

[rigel]

Optimal captcha is limited use of captcha.

Use no captcha at first then enble it only for users/ips abusing the service

[ondratra]

Optimal captcha is limited use of captcha.

Use no captcha at first then enble it only for users/ips abusing the service

Good point. I will try this stance. I will cover only the most important flows with capthca and on other forms I will use it only for occasions of 3 bad attemps to login etc.

Thank you bitcointalk users. This topic is usefull for me